scholarly journals Physiological and Molecular Responses to Main Environmental Stressors of Microalgae and Bacteria in Polar Marine Environments

2020 ◽  
Vol 8 (12) ◽  
pp. 1957
Author(s):  
Chiara Lauritano ◽  
Carmen Rizzo ◽  
Angelina Lo Giudice ◽  
Maria Saggiomo
Keyword(s):  
Species Abundance ◽  
Co2 Concentration ◽  
The Arctic ◽  
Specific Gene ◽  
Marine Environments ◽  
Low Light ◽  
Molecular Responses ◽  
Polar Species ◽  
Ice Binding ◽  
Abundance And Distribution

The Arctic and Antarctic regions constitute 14% of the total biosphere. Although they differ in their physiographic characteristics, both are strongly affected by snow and ice cover changes, extreme photoperiods and low temperatures, and are still largely unexplored compared to more accessible sites. This review focuses on microalgae and bacteria from polar marine environments and, in particular, on their physiological and molecular responses to harsh environmental conditions. The data reported in this manuscript show that exposure to cold, increase in CO2 concentration and salinity, high/low light, and/or combination of stressors induce variations in species abundance and distribution for both polar bacteria and microalgae, as well as changes in growth rate and increase in cryoprotective compounds. The use of -omics techniques also allowed to identify specific gene losses and gains which could have contributed to polar environmental adaptation, and metabolic shifts, especially related to lipid metabolism and defence systems, such as the up-regulation of ice binding proteins, chaperones and antioxidant enzymes. However, this review also provides evidence that -omics resources for polar species are still few and several sequences still have unknown functions, highlighting the need to further explore polar environments, the biology and ecology of the inhabiting bacteria and microalgae, and their interactions.

scholarly journals Polarella glacialis genomes encode tandem repeats of single-exon genes with functions critical to adaptation of dinoflagellates

2019 ◽  
Author(s):  
Timothy G. Stephens ◽  
Raúl A. González-Pech ◽  
Yuanyuan Cheng ◽  
Amin R. Mohamed ◽  
David W. Burt ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Genome Structure ◽  
The Arctic ◽  
Genome Comparison ◽  
Long Terminal Repeats ◽  
Transcriptional Responses ◽  
Low Light ◽  
Binding Domains ◽  
Ice Binding ◽  
Genome Assemblies

AbstractDinoflagellates are taxonomically diverse, ecologically important phytoplankton in marine and freshwater environments. Here, we present two draft diploid genome assemblies of the free-living dinoflagellate Polarella glacialis, isolated from the Arctic and Antarctica. For each genome, guided using full-length transcriptome data, we predicted >50,000 high-quality genes. About 68% of the genome is repetitive sequence; long terminal repeats likely contribute to intra-species structural divergence and distinct genome sizes (3.0 and 2.7 Gbp). Of all genes, ∼40% are encoded unidirectionally, ∼25% comprised of single exons. Multi-genome comparison unveiled genes specific to P. glacialis and a common, putatively bacterial, origin of ice-binding domains in cold-adapted dinoflagellates. Our results elucidate how selection acts within the context of a complex genome structure to facilitate local adaptation. Since most dinoflagellate genes are constitutively expressed, Polarella glacialis has enhanced transcriptional responses via unidirectional, tandem duplication of single-exon genes that encode functions critical to survival in cold, low-light environments.

scholarly journals Light and CO2 Modulate the Accumulation and Localization of Phenolic Compounds in Barley Leaves

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 385
Author(s):  
Lena Hunt ◽  
Karel Klem ◽  
Zuzana Lhotáková ◽  
Stanislav Vosolsobě ◽  
Michal Oravec ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Phenolic Compounds ◽  
Co2 Concentration ◽  
Environmental Stressors ◽  
Low Light ◽  
Mesophyll Cells ◽  
Stress Prevention ◽  
Tolerant Variety ◽  
Barley Leaves

Barley (Hordeum vulgare) accumulates phenolic compounds (PhCs), which play a key role in plant defense against environmental stressors as antioxidants or UV screening compounds. The influence of light and atmospheric CO2 concentration ([CO2]) on the accumulation and localization of PhCs in barley leaves was examined for two varieties with different tolerances to oxidative stress. PhC localization was visualized in vivo using fluorescence microscopy. Close relationships were found between fluorescence-determined localization of PhCs in barley leaves and PhC content estimated using liquid chromatography coupled with mass spectroscopy detection. Light intensity had the strongest effect on the accumulation of PhCs, but the total PhC content was similar at elevated [CO2], minimizing the differences between high and low light. PhCs localized preferentially near the surfaces of leaves, but under low light, an increasing allocation of PhCs in deeper mesophyll layers was observed. The PhC profile was significantly different between barley varieties. The relatively tolerant variety accumulated significantly more hydroxycinnamic acids, indicating that these PhCs may play a more prominent role in oxidative stress prevention. Our research presents novel evidence that [CO2] modulates the accumulation of PhCs in barley leaves. Mesophyll cells, rather than epidermal cells, were most responsive to environmental stimuli in terms of PhC accumulation.

Identification and analysis of two sequences encoding ice-binding proteins obtained from a putative bacterial symbiont of the psychrophilic Antarctic ciliate Euplotes focardii

2014 ◽  
Vol 26 (5) ◽  
pp. 491-501 ◽  
Author(s):  
Sandra Pucciarelli ◽  
Federica Chiappori ◽  
Raghul Rajan Devaraj ◽  
Guang Yang ◽  
Ting Yu ◽  
...  
Keyword(s):  
Amino Acid Level ◽  
Bacterial Symbiont ◽  
The Arctic ◽  
Glacial Ice ◽  
Mould Fungus ◽  
Lake Vostok ◽  
Ice Binding ◽  
Stigmatella Aurantiaca ◽  
Ice Binding Protein ◽  
The Antarctic

AbstractWe identified two ice-binding protein (IBP) sequences, named EFsymbAFP and EFsymbIBP, from a putative bacterial symbiont of the Antarctic psychrophilic ciliate Euplotes focardii. EFsymbAFP is 57.43% identical to the antifreeze protein (AFP) from the Stigmatella aurantiaca strain DW4/3-1, which was isolated from the Victoria Valley lower glacier. EFsymbIBP is 53.38% identical to the IBP from the Flavobacteriaceae bacterium strain 3519-10, isolated from the glacial ice of Lake Vostok. EFsymbAFP and EFsymbIBP are 31.73% identical at the amino acid level and are organized in tandem on the bacterial chromosome. The relatively low sequence identity and the tandem organization, which appears unique to this symbiont, suggest an occurrence of horizontal gene transfer (HGT). Structurally, EFsymbAFP and EFsymbIBP are similar to the AFPs from the snow mould fungus Typhula ishikariensis and from the Arctic yeast Leucosporidium sp. AY30. A phylogenetic analysis showed that EFsymbAFP and EFsymbIBP cluster principally with the IBP sequences from other Antarctic bacteria, supporting the view that these sequences belong to an Antarctic symbiontic bacterium of E. focardii. These results confirm that IBPs have a complex evolutionary history, which includes HGT events, most probably due to the demands of the environment and the need for rapid adaptation.

scholarly journals Within-Arctic horizontal gene transfer as a driver of convergent evolution in distantly related microalgae

2021 ◽  
Author(s):  
Richard G Dorrell ◽  
Alan Kuo ◽  
Zoltan Fussy ◽  
Elisabeth H Richardson ◽  
Asaf Salamov ◽  
...  
Keyword(s):  
Sequence Data ◽  
Sequence Similarity ◽  
Algal Species ◽  
Gene Families ◽  
The Arctic ◽  
Arctic Water ◽  
Diverse Range ◽  
Binding Domains ◽  
Ice Binding ◽  
Ice Conditions

The Arctic Ocean is being impacted by warming temperatures, increasing freshwater and highly variable ice conditions. The microalgal communities underpinning Arctic marine food webs, once thought to be dominated by diatoms, include a phylogenetically diverse range of small algal species, whose biology remains poorly understood. Here, we present genome sequences of a cryptomonad, a haptophyte, a chrysophyte, and a pelagophyte, isolated from the Arctic water column and ice. Comparing protein family distributions and sequence similarity across a densely-sampled set of algal genomes and transcriptomes, we note striking convergences in the biology of distantly related small Arctic algae, compared to non-Arctic relatives; although this convergence is largely exclusive of Arctic diatoms. Using high-throughput phylogenetic approaches, incorporating environmental sequence data from Tara Oceans, we demonstrate that this convergence was partly explained by horizontal gene transfers (HGT) between Arctic species, in over at least 30 other discrete gene families, and most notably in ice-binding domains (IBD). These Arctic-specific genes have been repeatedly transferred between Arctic algae, and are independent of equivalent HGTs in the Antarctic Southern Ocean. Our data provide insights into the specialised Arctic marine microbiome, and underlines the role of geographically-limited HGT as a driver of environmental adaptation in eukaryotic algae.

scholarly journals Warm Paleocene/Eocene climate as simulated in ECHAM5/MPI-OM

2009 ◽  
Vol 5 (3) ◽  
pp. 1297-1336 ◽  
Author(s):  
M. Heinemann ◽  
J. H. Jungclaus ◽  
J. Marotzke
Keyword(s):  
Temperature Difference ◽  
Radiative Forcing ◽  
Co2 Concentration ◽  
The Arctic ◽  
Balance Model ◽  
Proxy Data ◽  
Reference Simulation ◽  
Low Latitudes ◽  
Planetary Albedo ◽  
Temperature Proxy

Abstract. We investigate the late Paleocene/early Eocene (PE) climate using the coupled atmosphere-ocean-sea ice model ECHAM5/MPI-OM. The surface in our PE control simulation is on average 297 K warm and ice-free, despite a moderate CO2 concentration of 560 ppm. Compared to a pre-industrial reference simulation (PR), low latitudes are 5 to 8 K warmer, while high latitudes are up to 40 K warmer. This high-latitude amplification is in line with proxy data, yet a comparison to sea surface temperature proxy data suggests that the Arctic surface temperatures are still too low. To identify the mechanisms that cause the PE-PR temperature difference, we fit a zero-dimensional energy balance model to the ECHAM5/MPI-OM results. Doubled pCO2 in PE compared to PR, increased atmospheric water vapour, and a slightly increased longwave cloud radiative forcing together cause about 2/3 of the PE-PR temperature difference; planetary albedo changes cause about 1/3. Our results support the hypothesis that local radiative effects as well as topographic changes, rather than increased meridional heat transports, were responsible for the "equable" PE climate.

Type II Ice-Binding Proteins Isolated from an Arctic Microalga Are Similar to Adhesin-Like Proteins and Increase Freezing Tolerance in Transgenic Plants

2019 ◽  
Vol 60 (12) ◽  
pp. 2744-2757 ◽  
Author(s):  
Sung Mi Cho ◽  
Sanghee Kim ◽  
Hojin Cho ◽  
Hyoungseok Lee ◽  
Jun Hyuck Lee ◽  
...  
Keyword(s):  
Low Temperature ◽  
Transgenic Plants ◽  
Freezing Tolerance ◽  
Binding Proteins ◽  
The Arctic ◽  
Ice Recrystallization Inhibition ◽  
Ice Binding ◽  
Antarctic Snow ◽  
Vitro Analysis

Abstract Microalgal ice-binding proteins (IBPs) in the polar region are poorly understood at the genome-wide level, although they are important for cold adaptation. Through the transcriptome study with the Arctic green alga Chloromonas sp. KNF0032, we identified six Chloromonas IBP genes (CmIBPs), homologous with the previously reported IBPs from Antarctic snow alga CCMP681 and Antarctic Chloromonas sp. They were organized with multiple exon/intron structures and low-temperature-responsive cis-elements in their promoters and abundantly expressed at low temperature. The biological functions of three representative CmIBPs (CmIBP1, CmIBP2 and CmIBP3) were tested using in vitro analysis and transgenic plant system. CmIBP1 had the most effective ice recrystallization inhibition (IRI) activities in both in vitro and transgenic plants, and CmIBP2 and CmIBP3 had followed. All transgenic plants grown under nonacclimated condition were freezing tolerant, and especially 35S::CmIBP1 plants were most effective. After cold acclimation, only 35S::CmIBP2 plants showed slightly increased freezing tolerance. Structurally, the CmIBPs were predicted to have β-solenoid forms with parallel β-sheets and repeated TXT motifs. The repeated TXT structure of CmIBPs appears similar to the AidA domain-containing adhesin-like proteins from methanogens. We have shown that the AidA domain has IRI activity as CmIBPs and phylogenetic analysis also supported that the AidA domains are monophyletic with ice-binding domain of CmIBPs, and these results suggest that CmIBPs are a type of modified adhesins.

Intestinal parasites of the Arctic fox in relation to the abundance and distribution of intermediate hosts

Parasitology ◽  
2009 ◽  
Vol 137 (1) ◽  
pp. 149-157 ◽  
Author(s):  
A. STIEN ◽  
L. VOUTILAINEN ◽  
V. HAUKISALMI ◽  
E. FUGLEI ◽  
T. MØRK ◽  
...  
Keyword(s):  
Intermediate Host ◽  
Intestinal Parasites ◽  
Parasite Community ◽  
Host Population ◽  
The Arctic ◽  
Arctic Fox ◽  
Vole Population ◽  
Intermediate Hosts ◽  
Svalbard Archipelago ◽  
Abundance And Distribution

SUMMARYThe intestinal parasite community of Arctic foxes (Vulpes lagopus) on the Svalbard archipelago in the High Arctic was investigated in relation to the abundance and distribution of intermediate hosts. Five species of cestodes (Echinococcus multilocularis, Taenia crassiceps, Taenia polyacantha, Taenia krabbei and Diphyllobothrium sp.), ascaridoid nematodes and one unidentified acanthocephalan species were found. The cestodes E. multilocularis, T. crassiceps and T. polyacantha all showed a decreasing prevalence in the fox population with increasing distance from their spatially restricted intermediate host population of sibling voles (Microtus levis). In addition, the prevalence of E. multilocularis in a sample from the vole population was directly related to the local vole abundance. The cestode T. krabbei uses reindeer as intermediate host, and its prevalence in female foxes was positively related to the density of reindeer (Rangifer tarandus platyrhyncus). Finally, the prevalence of the ascaridoid nematodes also decreased with increasing distance from the vole population, a finding that is consistent with the idea that voles are involved in transmission, most likely as paratenic hosts. The prevalence of the remaining species (Diphyllobothrium sp. and an unidentified acanthocephalan) was very low. We conclude that the distribution and abundance of intermediate host structure the gastrointestinal parasite community of the Arctic fox on the Svalbard archipelago.

Light intensity and the growth of Eucalyptus seedlings. I. Ontogenetic variation in E. fastigata

1970 ◽  
Vol 18 (1) ◽  
pp. 29 ◽  
Author(s):  
RJ Cameron
Keyword(s):  
Enzyme Activity ◽  
Light Intensity ◽  
Morphological Characteristics ◽  
Anatomical Structure ◽  
Growth Stages ◽  
Ontogenetic Variation ◽  
Light Climate ◽  
Low Light ◽  
Adult Leaf ◽  
Abundance And Distribution

Morphological and physiological variation associated with ontogenetic development is described for E. fastigata and their significance in ecology is discussed. Juvenile, intermediate, and adult leaf stages are identified. These differ in such morphological characteristics as leaf orientation, shape, thickness, chlorophyll content, and anatomical structure (including size, abundance, and distribution of stomata), all details which, in juvenile and intermediate leaves at least, are modified by the light climate under which the plants are grown. There are also significant physiological differences between juvenile and intermediate growth stages, particularly as concern apical dominance and rates of apparent photosynthesis, and modification of these by light climate. A comparison of juvenile and intermediate leaves shows that the former possess a number of features which should permit them to function better in conditions of low light intensity but, contrary to such expectations, rates of apparent photosynthesis are higher in intermediate leaves. That this is so is, it is suggested, due to differences in photosynthetic enzyme activity, an hypothesis which has not been investigated.

scholarly journals AUTOMATIC FISH DETECTION FROM DIFFERENT MARINE ENVIRONMENTS VIDEO USING DEEP LEARNING

2022 ◽  
Vol XLVI-4/W3-2021 ◽  
pp. 191-198
Author(s):  
A. Loulidi ◽  
R. Houssa ◽  
L. Buhl-Mortensen ◽  
H. Zidane ◽  
H. Rhinane
Keyword(s):  
Deep Learning ◽  
Fish Species ◽  
Data Augmentation ◽  
Atlantic Coast ◽  
Training Dataset ◽  
Optimization Approach ◽  
Marine Environments ◽  
Low Light ◽  
Fish Detection ◽  
Performance Results

Abstract. The marine environment provides many ecosystems that support habitats biodiversity. Benthic habitats and fish species associations are investigated using underwater gears to secure and manage these marine ecosystems in a sustainable manner. The current study evaluates the possibility of using deep learning methods in particular the You Only Look Once version 3 algorithm to detect fish in different environments such as; different shading, low light, and high noise within images and by each frame within an underwater video, recorded in the Atlantic Coast of Morocco. The training dataset was collected from Open Images Dataset V6, a total of 1295 Fish images were captured and split into a training set and a test set. An optimization approach was applied to the YOLOv3 algorithm which is data augmentation transformation to provide more learning samples. The mean average precision (mAP) metric was applied to measure the YOLOv3 model’s performance. Results of this study revealed with a mAP of 91,3% the proposed method is proved to have the capability of detecting fish species in different natural marine environments also it has the potential to be applied to detect other underwater species and substratum.

scholarly journals Avifauna in Relation to Habitat Disturbance in Wildlife Management Areas of the Ruvuma Miombo Ecosystem, Southern Tanzania

2021 ◽  
Author(s):  
Ally K. Nkwabi ◽  
John K. Bukombe ◽  
Hamza K. Kija ◽  
Steven D. Liseki ◽  
Sood A. Ndimuligo ◽  
...  
Keyword(s):  
Wildlife Management ◽  
Species Abundance ◽  
Habitat Types ◽  
Point Count ◽  
Riverine Forest ◽  
Study Sites ◽  
Prompt Action ◽  
Abundance And Distribution ◽  
Open Woodland ◽  
Wildlife Management Areas

Understanding of relative distribution of avifauna provides insights for the conservation and management of wildlife in the community managed areas. This study examined relative diversity, abundance, and distribution of avifauna in selected habitat types across five Wildlife Management Areas of the Ruvuma landscape in miombo vegetation, southern Tanzania. Five habitat types were surveyed during the study: farmland, swamps, riverine forest, dense and open woodland. Transect lines, mist-netting, and point count methods were used to document 156 species of birds in the study sites. Descriptive statistics and Kruskal-Wallis tests were used to compare species richness and diversity across habitat types. We found differences in avifaunal species distribution in the study area whereby farmland had the highest abundance of avifauna species and lowest in the riverine forest. These results suggest that variations of avifauna species abundance, diversity, and distribution could be attributed by human activities across habitat types; due to the reason that habitats with less human encroachment had good species diversity and richness. Therefore, to improve avitourism and avoid local extinction of species, we urge for prompt action to mitigate species loss by creating awareness in the adjacent community through conservation education on the importance of protecting such biodiversity resources.

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